Denniston - the team player
In the early weeks of WW1, when Room 40 could make no progress against German codes, Denniston was among those sent to assist the War Office's small cryptanalytic unit eventually known as MI1b. It was here that he first saw the value of international collaboration when the French shared the fruits of their considerable experience of cryptanalysis of German traffic. After the capture of Imperial German Navy (IGN) codebooks, Fleet Paymaster Rotter in Room 40 made a breakthrough by working out the system being used by the IGN to superencipher encoded messages. Denniston and the others then returned to the Admiralty where he worked on both naval and diplomatic traffic for the rest of the war.
In 1917, Denniston's belief in the value of international cooperation was strengthened when he saw the way in which the Director of Naval Intelligence, Admiral Hall, fed intelligence to the US Embassy in London to shape US policy, a relationship which eventually allowed the Admiralty to use the Zimmermann Telegram to influence President Wilson and US public opinion to the point at which American neutrality towards Germany became untenable.
In 1938, as war became inevitable, he would again look to international partners to secure strategic advantage for Britain. At the suggestion of the French, he began talks with the Polish, who had been very successful in tackling German signals methods and capabilities. A more chauvinistic individual might have dismissed Polish methods, deeming British approaches superior, but this was not Denniston's style. The cordial relations established with the Poles significantly advanced GC&CS's work against Enigma.
Before his demotion and organisational exile in 1942, Denniston had one more major contribution to make to partnerships, and one that left a significant and lasting legacy. In 1941, President Roosevelt decided to expand cooperation with the UK, with one of the first steps being to send a team of cryptanalysts to Bletchley Park, who were given as complete access to GC&CS as 'C' would allow. Later in 1941, but still before the USA entered the war, Denniston visited Washington DC. The commitment to collaboration he displayed during these visits helped lay the foundations of the intelligence and security partnership that endures to this day between the UK and its allies.
Denniston's willingness to develop international partnerships was one manifestation of his collegiate and inclusive attitude, and attitude equally evident in his approach to managing GC&CS. By providing an environment that encouraged individuality and harnessed it to a common goal, Denniston allowed the famous - such as Alan Turing, Dilly Knox, and Gordon Welchman - and the (undeservedly) less famous - Hugh Foss, Emily Anderson, Mavis Batey, Ernst Fetterlein, and many others - to give the best to 'his' team.